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What is the role of graphite rod in the electrometallurgy of aluminium?A. It acts as anodeB. It acts as cathodeC. It acts as oxidising agentD. Both (a) and (c) |
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Answer» Correct Answer - A Graphite rods act as anode during the electrolytic reduction of alumina (Hall-Heroult process). At anode , `O_(2)` gas is produced which reacts with the carbon of anode (rods ) to produce `CO_(2)` gas , so these graphite rods are consumed slowly and need to be replaced from time to time. `Al_(2)O_(3) iff 2Al^(3+) +3O^(2-)` At cathode `Al^(3+) +3e^(-) to Al ` At anode `3O^(2-) to 3[O]+6e^(-) xx 2 ` `or 3[O]+3[O] to3O_(2)` `C(s)+O_(2)(g) to CO_(2)(g)` |
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